I am using MariaDB (1 master, 1 slave, 1 backup slave) for any site that does 5 million page sights daily contributing to 3000 queries per second at peak time.

To be sure it "just works" which it works much better than MySQL.

The only real issues that I've experienced within the ~12 months that I have used it happen to be 2 MySQL bugs and also the Maria team continues to be quick to repair individuals bugs.

I really like it and I would suggest that everyone (regardless of what their require is) use MariaDB over MySQL. MariaDB is really a better MySQL. MariaDB includes the (awesome) InnoDB Wordpress plugin, Percona performance patches featuring, as well as an active team of developers that frequently fixes MySQL bugs age range before they reveal up within an official MySQL release.

Update - September 2011

MySQL 5.5 continues to be out for some time and 5.6 is searching great.

The MariaDB team has not launched a version of MariaDB that's according to MySQL 5.5. They've, however, added some optimizations that MySQL customers have wanted for any looong time. http://kb.askmonty.org/en/what-is-mariadb-53

You will find some +100,000 of downloads of MariaDB, but in comparison to MySQL 10-50M customers, MariaDB continues to be small.

As we're not monitoring customers, it's difficult to understand who's using MariaDB. What I know is the fact that among guests in free conferences, MariaDB is began to obtain well-known Up from some ten percent -> forty percent throughout the this past year.. It's taken a while for this the planet to spread. The greatest reason is most likely that as lengthy as Oracle was 'playing it safe with MySQL' there is not grounds for many to find an alternate and when you aren't searching you won't find...